The prior art has attempted to provide several solutions to the basic need of supporting a wheeled vehicle with a device other than its road wheel, while the vehicle is repaired, restored or worked upon. As will appear, all have had problems associated with them and did not provide an ideal working condition.
For instance, the use of an ordinary jack failed to solve the problem because it cannot support a vehicle in a stable manner, and will not allow the vehicle when so supported to be moved. Damage to the vehicle and/or injury to the people working on a vehicle supported by an ordinary jack can easily result.
The use of a rolling hydraulic jack or floor jack was somewhat safer but it was also extremely difficult to relocate a vehicle because of the severe radial limitations provided by such devices. Nor did placing the vehicle so that it was supported by four hydraulic jacks solve the problem because movement would cause one or more of the jacks to become dislodged thereby potentially causing damage to the vehicle and/or injury to the mechanic.
Rivolta (U.S. Pat. No. 3,317,218) proposed a scissors-like support device having castors which can be attached in place of a wheel with the wheel lug nuts and an associated support plate which would support different types of vehicles at different heights. Rivolta's device suffered stability problems because of the distribution of the weight on the device and the excessive torque applied to the scissors joint when the vehicle so supported was moved in a direction other than in line with the plane of the device.
Chartier (U.S. Pat. No. 3,635,434) tried to solve the problem by providing a caster-mounted base plate having a pair of up-reaching arms for connection to the wheel lug bolts. Like Rivolta, Chartier had stability and safety problems which arose from the torque generated upon stress bearing parts of the device and the supported vehicle. Furthermore, Chartier provided only limited mobility when the supported vehicle was moved.
Thus a need still exists for a portable support device for replacing the wheels of a motor vehicle which provides enhanced mobility, stability and mechanic safety and simultaneously avoids the creation of adverse torque forces upon either the vehicle or the deivce so that further damage is avoided.
It is toward the solution of these needs that the present invention is directed.